LONDON, England (CNN) -- Apple's iPods and other portable MP3 players may not be radios, but that does not mean you cannot listen to radio broadcasts on them.

Podcasting is the technology that allows it to happen and, like the iPods themselves, the trend is becoming increasingly popular.

MP3 players do not have aerials, which means information cannot be broadcast via waves.

But as more and more radio stations stream their output on the Internet, programs can be downloaded as digital audio files and played on a portable MP3 player.

The trick with Podcasting, though, is that users do not have to visit a Web site to get the files delivered to their portable player -- the software steers them there automatically so you can play them when you are ready.

Former MTV host Adam Curry is the brains behind the technology that allows Podcasting to happen.

Curry says he wanted to come up with a less time-consuming way than manually transferring tracks from his PC to his iPod.

The UK-based American co-wrote the "iPodder" software, which automatically sends newly-posted audio files to an MP3 player's music management software as soon as they arrive online.

It also allows people to make their own radio station, and the craze is catching on.

Curry told CNN that Podcasting was about finding another use for a technology, different from the use for which it was originally intended.

"From a technology point of view, it is not hard at all to create a Podcast. It's funny these days, it comes with a microphone but no software. There is plenty of software that comes with your computer to create music. We are kind of forcing that software to create a different type of audio program."

He said Podcasting was a hobby for some people, just like Web logging or "blogging" is.

"I think a lot of people doing these things -- just like with web logs -- are not in it for the money. They are expressing an opinion," he said.

Curry hopes Podcasting will eventually be able to automatically transfer files via a wireless connection. At the moment it automatically downloads the files, but the user must log on to a computer to retrieve them.

"You still have to connect to your computer. It would be much more effective to have everything built into the iPod or MP3 player itself. So, whenever I walk into my home, my iPod will automatically download the Podcast that is there."